One of the first devices of this type was disclosed by U.S. Pat. No. 5,440,326. In this device, gyroscopes afford two measurements of angular velocities (in terms of pitch and yaw) which are converted into cursor commands in relation to two axes of the display surface. However, this type of device exhibits limitations in its ergonomics, since it is based only on the rate of rotation of the pointer in relation to 2 axes, measured in the frame of the pointer, and not on the orientation of the device in the display frame. For example, these measurements are sensitive to the orientation in which the pointer is held by the user (the 3rd angle, roll or tilt, not measured). Indeed, when the user holds the remote control with an angle of twist of their wrist (called roll), will see the cursor move in an undesired direction. Moreover, the limitation to two measurement axes renders the use of the remote control complex for significant angles and the ergonomics of the pointing is then affected thereby.
To combat these effects, a stabilization of the measurements can be performed by mechanical means, the gyroscopes being mounted on gimbals. However, this mechanical stabilization is on the one hand limited to small angles of roll (mechanical stops) and is imperfect also because of the inertia of the gimbals. Furthermore, such a correction is not applicable to miniature devices.
These drawbacks may to some extent be overcome by devices in which the measurements of rate of rotation in yaw and pitch provided by miniature gyrometers are corrected for the angle of roll by the measurements of an accelerometer using a two-dimensional rotation matrix. Devices of this nature are notably disclosed by U.S. Pat. No. 5,598,187 (Ide) and U.S. Pat. No. 7,158,118 (Liberty). In devices of this nature, the various angles must actually be computed on the basis of the measurements of different sensors. In the international application published under No. WO2009/156476 (Mathews) belonging to the applicant of the present application, a correction is applied without prior computation of the angle of roll. The roll angle correction in fact relies on a principle which is fundamentally imperfect to the extent that the accelerometer is also sensitive to the acceleration due to the motion, thereby inevitably perturbing the estimation of the angle of roll and giving an inaccurate effect on the trajectory of the cursor on the display surface. Finally, certain orientations of the pointer (near vertical, for example) no longer make it possible to compute the angle of roll, since the latter is no longer measured by the accelerometer. The roll compensation function therefore introduces on this occasion defects which are not present initially in the ergonomics of the control of the cursor by motion.
A way of overcoming the drawback of separate estimation of the angles has been disclosed by the international application published under the No. WO2009/156499, one of the proprietors of which is the proprietor of the present application, in which an extended Kalman filter is applied to carry out joint estimation of the state variables by using a state model comprising a first-order differential equation.
However, the implementation of this filtering is limited to a single mode of control of the movement of the cursor as a function of the movement of the pointer and is also greedy in terms of computation power.
Patent application US2004/070564 discloses a device for pointing on a screen which computes the displacements of a cursor on said screen on the basis of the coordinates of the intersection of a vector carried by the pointer with the screen. U.S. Pat. No. 7,102,616 discloses a device for pointing on a screen instrumented with sources in communication with said pointer which computes the displacements of the pointer on the basis of the angular velocity of the pointer in the frame of the screen. None of these documents discloses modalities for projecting the position and/or the orientation of the pointer on the cursor which are parametrizable as a function of the applicational context.